Resist material and fabrication method thereof

ABSTRACT

A resist material having a resist and particles mixed into the resist, a major component of the particles being a cluster of carbon atoms, is provided. A method for fabricating a resist material is also provided, the method repeatedly performing: a first step of coating a substrate with a resist film; and a second step of depositing particles whose major component is a cluster of carbon atoms on the resist film. Accordingly, a resist film with high etching resistance can be obtained, and it is possible to realize a reduction in the thickness of the resist film, improvements of contrast of resist patterns; resist sensitivity; heat resistance of resist films; mechanical strength of resist patterns; and further, stabilization of resist sensitivity. Therefore, highly precise fine pattern fabrication can be realized.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to resist materials for fabricating a finepattern and fabrication method of a resist material. This application isbased on patent applications Nos. Hei 8-166607, Hei 8-242560, and Hei9-038538 filed in Japan, the contents of which are incorporated hereinby reference.

2. Description of the Related Art

Pattern fabrication in relation to semiconductor integrated devicesrepresented by ULSI (Ultra Large Scale Integrated Circuit) is performedsuch that a thin film layer of a resist material (often abbreviated as a“resist”, hereinafter), which is sensitive to high energy beams such asUltra-violet light (often abbreviated as a “UV”, hereinafter), X-ray, orelectron beams, is deposited on a semiconductor substrate, and then theresist is irradiated with such high energy beams and is developed.

FIGS. 3A-3B are diagrams for explaining processes for fabricating apattern using a conventional resist material. In FIGS. 3A-3B, referencenumeral 1 indicates a (semiconductor) substrate, reference numeral 2indicates a resist film, reference numeral 3 indicates high energy beams(such as UV, X-ray, or electron beams), and reference numeral 4indicates reactive etching species. Accordingly, it is necessary for theresist materials (i) to have high sensitivity to high-energy beams inconsideration of quick pattern fabrication, (ii) to be keenly sensitiveto the high energy beams so as to obtain high pattern-resolutioncapability, and (iii) to have high etching resistance in the etching ofsemiconductor-substrate. Generally, the thinner the resist film is, thesmaller the spreading of the high energy beam is in the resist film;thus, pattern resolution is increased. Similarly, due to thinner resistfilms, etched pattern transfer difference from a resist pattern becomessmaller; thus, fabrication precision in the substrate etching isimproved. Therefore, the pattern fabrication has been performed with aresist film as thin as possible. In particular, in the research anddevelopment of most-advanced devices such as the next ULSI, orquantum-effect devices, pattern widths will be in a range between 10nm˜150 nm, thus thinning of resist films is much more necessary forrealizing miniaturization or nano-fabrication and higher precision.

The resist used for such ultra-fine processing can be generallyclassified into the following 5 types:

(1) a resist comprising an alkaline soluble resin and adiazonaphthoquinone-compound as a photo-sensitizer;

(2) an acrylic type polymer resist which degrades via main chainscission;

(3) a resist material comprising an alkaline soluble resin and an azideas a photo-sensitizer;

(4) a crosslinking type resist containing a chloromethyl group or anepoxy group; and

(5) a chemical amplification resist comprising an alkaline solubleresin, an acid generator, and a dissolution controlling agent having anacid sensitive group.

The resist material of type (1), generally used in LSI processing, isexposed to UV and the diazonaphthoquinone-compound as a sensitizer issubjected to a chemical change during UV exposure, by which solubilityof the alkaline soluble resin is enhanced and a pattern is fabricated.As the alkaline soluble resin, a novolac resin, a phenol resin,poly(hydroxy styrene), and the like are used; however, the novolac resinis most commonly used. This type of resist has been used for patternfabrication with a relatively thick film, approximately up to 200 nm.

The resist material of type (2) has mainly been used in the ultra-finepattern fabrication of 200 nm or less. In this type, the acrylic mainchains are cut by irradiating an electron beam, an X-ray, or UV having awavelength of 300 nm or less, by which solubility of the resist isenhanced and a pattern is fabricated. (i) Poly(methyl methacrylate)(i.e., PMMA), (ii) ZEP (manufactured by Nippon Zeon Co.) which is acopolymer of α-chloro methacrylate and α-methyl styrene, and (iii) poly2,2,2-trifluoroethyl α-chloro acrylate (e.g., EBR-9 manufactured byToray Co.) are representative resist materials of this type. In thistype of resist, the difference in solubility rates between exposed andunexposed areas is very large, hence very high resolution can berealized. Therefore, this type of resist is generally used in thin-filmform so as to fabricate an ultra-fine pattern of 200 nm or less.

As an example of fabricating a fine pattern of 10-50 nm range bythinning the resist film, it has been reported, in “Fabrication of 5-7nm wide etched lines in silicon using 100 keV electron-beam lithographyand polymethylmethacrylate resist”, Applied Physics Letters, Vol. 62(13), pp. 1499-1501, Mar. 29, 1993, that a Si substrate is dry-etchedthrough a mixture gas of SiCl₄ and CF₄ by using a 65 nm thick PMMAresist, a representative high-resolution resist. Another article, “Sinanostructures fabricated by electron beam lithography combined withimage reversal process using electron cyclotron resonance plasmaoxidation”, Journal of Vacuum Science and Technology, Vol. B13 (6), pp.2170-2174, November/December, 1995, also reported the use of a 50 nmthick ZEP resist, which is known to have resolution as good as PMMA andalso to have relatively high etching resistance for oxygen plasmaprocessing of substrate.

On the other hand, in the case of defining a relatively large nanometerpattern of 50-150 nm, necessary resolution can be achieved in thepresent circumstances by using a relatively thick PMMA or ZEP resist andhigh energy beams mentioned above. In this range of pattern size, it israther important to process substrates without forming any defectsduring dry-etching; then, the resist thickness is increased to ensurenecessary dry-etching resistance. Typical resist thickness for thispurpose is in a range of 0.1-0.5 μm.

The resist material of type (3) is normally used for UV or an electronbeam exposure. This type of resist comprises the azide as aphoto-sensitizer and the alkaline soluble resin, and the chemical changeof azide, and the UV or electron beam exposure makes alkaline solubleresin insoluble, resulting in the formation of negative type patterns.

The resist material of type (4) comprises polymer resins containing thechloromethyl group or the epoxy group which has high crosslinkingreactivity. In this type, the polymers are crosslinked with each otherwhen they are irradiated by UV, an electron beam, or an X-ray, and thepolymers become insoluble and a pattern is fabricated. This type of theresist is mainly used in negative-type pattern fabrication in whichexposed areas remain.

The resist material of type (5) comprises the alkaline soluble resin,the acid generator, and the dissolution controlling agent (it may alsobe called a dissolution inhibitor) having the acid sensitive group. Inthis type, an acid is generated from the acid generator throughirradiation of UV, electron beam, or X-ray, then, the acid reacts withthe acid sensitive group of the dissolution controlling agent, by whichthe solubility of the alkaline soluble resin is changed and a pattern isfabricated. Since the reaction between the acid and the dissolutioncontrolling agent proceeds via chain reaction scheme, very highsensitivity can be achieved in this type of resist. As the alkalinesoluble resin, a novolac resin, a phenol resin, poly(hydroxy styrene),and the like are used. Additionally, in the chemical amplification type,there are some variations such that (i) the alkaline soluble resinfunctions as a dissolution controlling agent having an acid sensitivegroup, or (ii) a resin having an acid sensitive group reacts with anacid, making the resin alkaline soluble. However, in this type ofresist, the acid becomes inactive due to water, ammonia, and the likeincluded in the air, hence the resist sensitivity is considerably variedwith the time between exposure and development. In order to stabilizedthe sensitivity, another polymer film to prevent the deactivators frompenetrating in the resist film are overcoated on the resist.

Hereinbelow, common problems relating to the resists of the above(1)-(5) types will be explained.

In the conventional fine-pattern fabrication methods, even if a resistwith relatively high resistance is used, minimum resist thickness forpractical pattern fabrication is limited to approximately 50 nm. Whenthe resist thickness is further reduced to get higher resolution, thereoccurs a problem that defects are generated on the processed substratedue to insufficient etching resistance of resist films, as shown in FIG.3C.

Particularly, the acrylic main chain scission type resists have normallylow etching resistance, because the main chain scission is also causedby etching reactive species; thus, it has been difficult to use thistype of resist as a direct etching mask in a process including dryetching.

In addition, FIG. 7 shows a scanning electron microscope (SEM)photograph of a 0.05 μm line-and-space pattern of thin resist. Asclearly shown from the photograph, there has been a problem in thatunderexposed areas just near irradiated areas are partially dissolvedduring the development and a fine pattern having a vertical sectionalform cannot be obtained.

Furthermore, when relatively thick resist of typically 0.2-0.5 μm forthe pattern fabrication of relatively large regime such as 50-150 nm isused to ensure sufficient etching resistance, the aspect ratio (i.e., aratio of the pattern height to the pattern width) of the resist patternmust be increased to 4, or more. The inventors of the present inventionfound a problem that such high aspect patterns tend to collapse in adrying process of rinse solvent used for the development, because of thesurface tension of the rinse solvent. As the collapse of high aspectratio patterns is related to the mechanical strength of the resist film,in the case of resist thickness of about 50 nm, which is almost theminimum thickness for a practical nanometer fabrication process, veryfine patterns around 10 nm wide tend to collapse since the aspect ratiois more than 4. Thus, the low mechanical strength of the resist film isa serious issue in nanometer pattern fabrication.

The inventors also paid attention to a time-dependent sensitivityproblem in chemical amplification resist using an acid generated byirradiation of high energy beams as a catalyst as mentioned above. Apolymer overcoat on the resist to stabilize sensitivity is inevitable inthis case and this causes more complicated processes. Furthermore, inthe case of thinner resist film which suffers more seriously from thisproblem, because deactivators such as water and ammonia can easilypenetrate through the film, the polymer overcoat is not sufficient tocompletely stabilize the resist sensitivity, thus it is very difficultto perform highly precise pattern fabrication.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a resist materialand a fabrication method thereof, by which the above-described problemswith respect to the fine pattern fabrication for semiconductorsubstrate, and the like, can be solved, and highly precise processing ofthe substrate can be realized.

Accordingly, the present invention provides a resist material having aresist and particles mixed into the resist, a major component of theparticles being a cluster of carbon atoms. The resist may be selectedfrom the following 5 types:

(1) a resist comprising an alkaline soluble resin and adiazonaphthoquinone-compound as a photo-sensitizer;

(2) an acrylic type polymer resist which degrades via main chainscission;

(3) a resist material comprising an alkaline soluble resin and an azideas a photo-sensitizer;

(4) a crosslinking type resist containing a chloromethyl group or anepoxy group; and

(5) a chemical amplification resist comprising an alkaline solubleresin, an acid generator, and a dissolution controlling agent having anacid sensitive group.

The present invention also provides a method for fabricating a resistmaterial, by repeatedly performing:

(1) a first step of coating a substrate with a resist film; and

(2) a second step of depositing particles whose major component is acluster of carbon atoms on the resist film.

The resist material of the present invention achieves two functions suchas

(i) closely packing the resist film with carbon particles because freespaces among resist molecules formed during spin-coating process arefilled up by the particles, and

(ii) inhibiting penetration of etching reactive species into the resistfilm and enhancing the etching resistance of the resist film because themajor component of the particles is a cluster of carbon atoms which hashigh etching resistance.

Regarding functions resulting from the high etching resistance of thecarbon atoms, for example, the article “Amorphous carbon films as resistmasks with high reactive ion etching resistance for nanometerlithography”, Applied Physics Letters, Vol. 48 (13), pp. 835-837, 1986,discloses that regarding oxygen plasma dry etching, a film consistingonly of a cluster of carbon atoms has etching resistance twice as highas that of a resist of a novolac resin base, the novolac resin beingknown to have higher etching resistance than the PMMA.

In addition to the enhancement of etching resistance according to thepresent invention, the penetration of developer molecules into the filmis suppressed, and consequently, the contrast of the resist pattern isimproved. This is because, as described in, for example, Vol. 5, page749, of Kagaku Daijiten (“Chemical Terms Dictionary”), published byKyoritsu Shuppan Publishing Co. in 1981, a cluster consisting of onlycarbon atoms is generally insoluble in organic and inorganic solvents,hence such a cluster is also insoluble in a resist developer in whichnormal organic and inorganic chemicals are used. If spaces in a resistfilm are filled with carbon particles having such characteristics, thesolubility of the resist is lowered. However, in a resist belonging tothe above types (1), (2), and (5), volatile components are generated inexposed areas, and these volatile components make it easier for thedeveloper molecules to penetrate the resist film. Accordingly, exposedand unexposed areas show large difference in solubilities, thus highresolution can be obtained.

Furthermore, in the chemical-amplification type resist materialaccording to the present invention, penetration of water, ammonia, andthe like, which makes an acid catalyst inactive, can be suppressed;thus, the sensitivity of the resist is stabilized.

In addition, such particles having a cluster of carbon atoms as a majorcomponent generally have high melting points in comparison with organicsubstances such as resists (for example, fullerene C₆₀, described below,has a melting point of 700° C. or more). Therefore, such fine carbonparticles with high melting points suppress the thermal movement ofresist molecules, and increase the heat resistance of the resistmaterial.

As particles having a cluster of carbon atoms as a major component,fullerene compounds of the so called “fullerene family” can be used. Thefullerene family which is characterized as having a spherical molecularstructure of carbon atoms includes fullerene C₆₀, high-order fullereneshaving more than 60 carbon atoms, a cylindrically elongated nanotube (akind of high-order fullerene), a metal-encapsulating fullerene in whicha metal is incorporated in its spherical molecular structure, and thelike. Among these compounds, fullerene compounds with smaller molecularsizes are more suitable for this invention, from the view point of thecapability of forming closely packed films with resists.

Fullerene derivatives, in which another atom such as a hydrogen or agroup such as a methyl group is combined with carbon atoms of thefullerene, are also effective in forming composite films with resists.As fullerene derivatives, any kinds can be used in principle. However,those having smaller molecular sizes are similarly desirable from a viewof the capability of forming closely packed film with resist.Furthermore, the fullerene derivatives with suitable functional groupswhich enhance the solubility in coating solvents for conventionalresists are the most desirable.

The mixtures of fullerene compounds mentioned above and mixtures offullerene compounds and fullerene derivatives can also be used for thisinvention.

The mechanical strength of the resist is improved by incorporation offullerene with resist, hence the above-mentioned problem, in which highaspect ratio patterns tend to collapse during the drying of rinsesolvents in the development process, can be solved.

As a further effect by incorporation of fullerene, the above-mentionedproblem relating to the chemical amplification resist, in which thesensitivity changes with time after exposure is solved because itbecomes more difficult for acid-deactivators to penetrate through aclosely packed composite resist film. Therefore, an extra process forstabilizing the sensitivity of a chemical amplification resist, such asover-coating, can be eliminated, thus, the fabrication processes aresimplified.

As an example of using the fullerene as a component of a resistmaterial, Japanese Patent Application, First Publication, Hei 6-167812has been known. The resist material disclosed in this publicationconsists of a fullerene and a photosensitive material. This resistbelongs to a type in which the resist is composed of a conventionalresin (such as the novolac resin) and a photosensitive material, and theuse of a fullerene or fullerene derivative instead of such a (novolac)resin is a feature of the material disclosed in the publication.Therefore, in this invention, a resin component in the resist is afullerene or fullerene derivative; thus, some of the above-mentionedproblems still remain, such as, the cost of the resist is increased, andconventional processes for treating resists have to be changed becausethe solvent used for the development is limited to those which willsufficiently dissolve fullerene and fullerene derivatives which arenormally used in conventional fabrication processes. Furthermore, thisinvention claims that the effect of the invention is the enhancement ofdry-etching durability, resulting in the increase of the sensitivity dueto the use of thinner resist.

In contrast, the resist materials in the present invention is thecomposite of carbon particles and conventional resist comprising a resinand a photosensitive material. As the carbon particles such as fullerenecompounds are additives to the conventional resist, the resist can bedeveloped using conventional developer, thus, no change in conventionalprocesses for treating the resist is required. Regarding the effect ofthe present invention, by incorporating carbon particles, variouscharacteristics of the resist such as etching resistance, resolution,heat resistance, mechanical strength, and sensitivity stability afterexposure can be greatly improved. Since the amount of carbon particlesto obtain above-mentioned various effects in the present invention issmall as compared with the resin and photosensitizer of conventionalresist, the cost of the resist material is not so much increased eventhough a currently expensive material is used, such as the fullerene.Therefore, the present invention is useful, and is superior incost-performance.

That is, according to the resist material and the fabrication methodthereof according to the present invention, a closely packed resist filmincorporated with carbon particles can be obtained, and it is possibleto realize various improvements of (i) dry-etching durability, (ii)contrast of resist patterns; (iii) resist sensitivity; (iv) heatresistance of resist films; (v) mechanical strength of resist patterns,and further, (vi) stabilization of resist sensitivity. Therefore, highlyprecise fine pattern fabrication can be realized. Furthermore,conventional developers and developing methods can be used in thefabrication process, and the resist after the substrate etching processcan be removed using either oxygen-plasma ashing and resist removersolution, thus, another effect relating to processing compatibility isobtained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1C are diagrams for explaining processes for fabricating apattern using a resist material according to the present invention.

FIGS. 2A-2C are diagrams for explaining an example of the method of thepresent invention for fabricating a resist material including particleswhose main component is a cluster of carbon atoms.

FIGS. 3A-3C are diagrams for explaining processes for fabricating apattern using a conventional resist material.

FIG. 4 is a graph diagram for comparing etching resistance durabilitiesof conventional resist materials and a resist material according to thepresent invention.

FIG. 5 is a graph diagram for comparing etching resistance durabilitiesof a conventional resist material and resist materials according to thepresent invention.

FIG. 6 is a SEM photograph of a fine pattern obtained in an example ofpattern fabrication using a resist material according to the presentinvention.

FIG. 7 is a SEM photograph of a fine pattern obtained in an example ofpattern fabrication using a conventional resist material.

FIG. 8 is a graph diagram for comparing sensitivity stabilities of aconventional resist material and a resist material according to thepresent invention.

FIG. 9 is a graph diagram for comparing sensitivity (plotted) curves ofa conventional resist material and a resist material according to thepresent invention.

FIG. 10 is a SEM photograph showing heat resistance of a fine patternobtained using a resist material according to the present invention.

FIG. 11 is a SEM photograph showing heat resistance of a fine patternobtained using a conventional resist material.

FIG. 12 is a SEM photograph showing mechanical strength of a finepattern obtained using a resist material according to the presentinvention.

FIG. 13 is a SEM photograph showing mechanical strength of a finepattern obtained using a conventional resist material.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinbelow, preferred embodiments of the present invention will beexplained in detail with reference to the drawings.

FIGS. 1A-1C are diagrams for explaining processes for fabricating apattern using a resist material according to the present invention. Inthe FIGS. 1A-1C, reference numerals 1-4 correspond to the same referencenumerals as shown in FIGS. 3A-3C, and reference numeral 5 indicatesparticles whose major component (that is, the major component of eachparticle) is a cluster of carbon atoms. As clearly shown by FIGS. 1A-1C,in the resist material according to the present invention, particleswhose major component is a cluster of carbon atoms are dispersed inspaces in the resist film.

Next, the fabrication method of a resist material according to thepresent invention will be explained with reference to FIGS. 2A-2C. Thatis, FIGS. 2A-2C are diagrams for explaining an example of the method ofthe present invention for fabricating a resist material includingparticles whose main component is a cluster of carbon atoms. In FIGS.2A-2C, reference numerals 1, 2, and 5 correspond to the same referencenumerals in FIGS. 1A-1C, and FIGS. 2A-2C correspond to the followingthree processes (a)-(c).

(a) First, a substrate is coated with a resist film, and is baked.

(b) Next, particles whose major component is a cluster of carbon atomsare deposited on the resist.

(c) processes (a) and (b) are repeated.

In this way, a resist film, in which a resist material of the presentinvention having a desired thickness is deposited, is obtained. Insteadof this method, a simpler method of making a resist material accordingto the present invention can be used.

This method is the spin-coating of the solution containing conventionalresist and particles whose main component is a cluster of carbon atoms.

Hereinbelow, resist materials and the fabrication method thereof inconnection with the present invention will be explained in detail basedon some practical embodiments; however, the present invention is notlimited to those embodiments.

In the following, the resists used in embodiments 1-5 and 7-15 belong tothe above type (2) described in the “Description of the Related Art”;the resists used in embodiments 6 and 16 belong to the above type (5);the resist used in embodiment 17 belongs to the above type (4); theresist used in embodiment 18 belongs to the above type (3); and theresist used in embodiment 19 belongs to the above type (1).

First Embodiment

The resist used in this embodiment is the above-mentioned PMMA(molecular weight: 600,000, manufactured by Tokyo Ohka Kogyo Co., Ltd.),a representative positive e-beam resist (that is, in this positive type,areas which are subjected to e-beam exposure are removed by development,as a result, a pattern is fabricated). For 100 parts by weight of thisPMMA, 1-50 parts by weight of particles whose main component is acluster of carbon atoms were incorporated so as to form a resistmaterial.

Hereinbelow, the method for fabricating the resist material in thepresent embodiment will be explained with reference to FIGS. 2A-2C.

Process 1 (see FIG. 2A): a Si substrate is spin-coated with the PMMAresist at a thickness of 10 nm, and the substrate is baked at 170° C.for 30 minutes.

Process 2 (see FIG. 2B): The Si substrate, on which the PMMA resist filmwas deposited, is put in a vacuum-discharge machine, and carbonparticles are deposited onto the PMMA resist film by discharging carbonelectrodes. In this process, the size and the amount of the carbonparticles to be formed can be controlled by adjusting the degree ofvacuum, discharge time, or the like. In this first embodiment, thedegree of vacuum was approximately 10⁻³ Torr; while the discharge timewas 0.2 sec, by which carbon particles having the size of 1 nm or lesscould be formed. Regarding the amount of deposited particles, the areacoated with the particles was set to be around 30% with respect to thesubstrate area. Here, the size of the particles and the depositionamount were measured using an atomic force microscope.

Process 3 (see FIG. 2C): By repeating the processes 1 and 2 after oncetaking out the above substrate from the vacuum-discharge machine, aresist material including carbon particles is obtained. In this case,when the substrate is baked after coating the top-layer PMMA, the carbonparticles which were deposited on lower layer PMMA film are moved by thethermal motion of the PMMA molecules, hence uniformity in thedistribution of carbon particles inside the film is improved. In thisfirst embodiment, the processes 1 and 2 were repeated by 5 times, bywhich a resist film of approximately 50 nm was obtained. Afterfabricating the resist film, a pattern fabrication experiment wasperformed using an electron beam exposure machine with 50 kVacceleration voltage. In the experiment, a conventional standarddeveloper for the PMMA (i.e., a 2/1 mixture of methyl isobutylketone/isopropyl alcohol) was used, and a 15 nm pattern could befabricated, where resolution as good as the conventional PMMA could beconfirmed.

The pattern contrast was evaluated by using a 0.05 μm line-and-spacepattern, with the same processing conditions as used in the aboveevaluation relating to the resolution. FIG. 6 shows a SEM photograph ofa pattern formed using the resist material according to the presentinvention and FIG. 7 shows a SEM photograph of a pattern formed usingthe conventional resist. As clearly shown by these photographs where thepattern edge becomes almost vertical, the pattern contrast is improvedin the case of the resist material of the present embodiment.

FIG. 4 shows a result of evaluation relating to dry-etching resistanceof the resist material according to the present invention in comparisonwith the conventional PMMA resist. In the figure, regarding the etchingrate ratio in the vertical axis, the etching rate of the resist materialof the first embodiment is set to be 1. In addition, black circles,white circles, and a rhombus respectively show results of the (pure)PMMA, the resist material of the present embodiment, and Si.

First, regarding reactive dry etching using O₂ gas for etching organicpolymer films, under etching conditions of gas flow: 20 SCCM; gaspressure: 2 Pa; and power: 50 W; the resist material of the firstembodiment had an etching rate of approximately 20% less than that ofthe PMMA; thus, the resistance was improved by this rate. On the otherhand, regarding ECR (electron cyclotron resonance) dry etching using Cl₂gas for etching a Si substrate, under etching conditions of gas flow: 40SCCM; gas pressure: 0.05 Pa; and microwave power: 200 W; the resist ofthe first embodiment had etching resistance approximately 3 times ashigh as that of the PMMA; thus, it was proved that by using a resistmaterial with a thickness approximately one third of the conventionalPMMA, substrate etching with an etching depth approximately as deep asthat of the conventional PMMA could be performed. Accordingly, as shownin FIGS. 1C and 3C, even with a film thickness which causes defects dueto the etching in a conventional resist, desirable substrate etchingwithout defects is realized using the resist material of the firstembodiment.

In this embodiment, a vacuum discharge method was used in the process ofdepositing carbon particles; however, another method may be used such asvacuum deposition of particles whose major component is a cluster ofcarbon atoms, sputter using a carbon target, or chemical vapordeposition (CVD) using a hydrocarbon gas, for example, methane,acetylene or ethylene. In these methods, impurities such as hydrogen andoxygen are generally included in the formed carbon particles; thus, itis difficult to form pure carbon particles. However, even in thosecases, etching resistance may still be improved in accordance withpurity of carbon particles.

Additionally, the above processes 1 and 2 were repeated five times andpattern fabrication was successively performed in this embodiment.However, for convenience of pattern fabrication, the two processes of(i) fabrication of a resist material and (ii) formation of a resist filmmay be separated. In this case, a resist material is first formed on asubstrate, and the resist material is dissolved using a coating solventso as to adjust a film thickness for coating. Then another substrate foretching is spin-coated with the dissolved material.

Second Embodiment

The resist used in this embodiment is also the above-mentioned PMMA(molecular weight: 600,000, manufactured by Tokyo Ohka Kogyo Co. Ltd), arepresentative positive e-beam resist. For 100 parts by weight of thisPMMA, 35 parts by weight of fullerene C₆₀ (manufactured by Tokyo KaseiCo.) were incorporated so as to form a resist material.

After dissolving the PMMA in methyl cellosolve acetate to have 10 wt %concentration and fullerene C₆₀ in monochlorobenzene to have 1 wt %concentration, both solutions were mixed to make a PMMA resist solutionincluding fullerene C₆₀. In order to evaluate the resolution of thisresist, a Si substrate was spin-coated with the resist at a thickness of50 nm, and after baking at 170° C. for 30 minutes, an exposureexperiment using the electron beam exposure machine (50 kV) wasperformed. In the experiment, the resist was developed using aconventional standard developer for the PMMA (i.e., a 2/1 mixture ofmethyl isobutyl ketone/isopropyl alcohol) for 3 minutes, and a 15 nmpattern could be fabricated, where resolution as good as theconventional PMMA could be recognized.

The pattern contrast was evaluated by using a 0.05 μm line-and-spacepattern, with the same processing conditions as used in the aboveevaluation of the resolution. As results of the evaluation, improvementof the pattern contrast was confirmed as in the first embodiment.

FIG. 5 shows a result of evaluation relating to dry-etching resistanceof the resist material according to the present embodiment in comparisonwith a conventional PMMA resist. In the figure, regarding the etchingrate ratio in the vertical axis, the etching rate of the (pure) PMMA isset to be 1. In addition, black circles, white triangles, and whitesquares respectively show results of the PMMA, the resist material ofthe second (present) embodiment, and the (later-explained) thirdembodiment.

First, regarding reactive dry etching using O₂ gas for etching organicpolymer films, under etching conditions of gas flow: 20 SCCM; gaspressure: 2 Pa; and power: 50 W; the resist material of the secondembodiment had an etching rate of approximately 20% less than that ofthe PMMA; thus, the resistance was improved by this rate. On the otherhand, regarding the ECR dry etching using Cl₂ gas for etching a Sisubstrate, under etching conditions of gas flow: 40 SCCM; gas pressure:0.05 Pa; and microwave power: 200 W; the resist of the second embodimenthad etching resistance approximately 2 times as high as that of thePMMA; thus, it was proved that by using a resist material with athickness approximately one half of the conventional PMMA, substrateetching with an etching depth approximately as deep as that of theconventional PMMA could be performed. Accordingly, as shown by FIGS. 1Cand 3C, even with a film thickness which causes defects due to theetching in a conventional resist, desirable substrate etching withoutdefects is realized using the resist material of the second embodiment.

Third Embodiment

The resist used in this embodiment is the PMMA (molecular weight:600,000, manufactured by Tokyo Ohka Kogyo Co. Ltd), and for 100 parts byweight of this PMMA, 35 parts by weight of hydrogenated fullerene C₆₀H₃₆(manufactured by MER Co.), which is obtained by adding hydrogen to thefullerene, were incorporated so as to form a resist material.

In order to evaluate the resolution of this resist, a Si substrate wasspin-coated with the resist at a thickness of 50 nm, and after baking at170° C. for 30 minutes, an exposure experiment using the electron beamexposure machine (50 kV) was performed. In the experiment, the resistwas developed using a conventional standard developer for the PMMA(i.e., a 2/1 mixtue of methyl isobutyl ketone/isopropyl alcohol) for 3minutes, and a 15 nm pattern could be fabricated as could in the secondembodiment, where resolution as good as the conventional PMMA could beconfirmed.

The pattern contrast was evaluated by using a 0.05 μm line-and-spacepattern, with the same processing conditions as used in the aboveevaluation of the resolution. As results of the evaluation, improvementof the pattern contrast was confirmed as in the first embodiment.

FIG. 5 shows a result of evaluation with respect to dry-etchingresistance of the resist material according to the present embodiment incomparison with the conventional PMMA resist. In the figure, regardingthe etching rate ratio in the vertical axis, the etching rate of thePMMA is set to be 1. First, regarding reactive dry etching using O₂ gasfor etching organic polymer films, under etching conditions of gas flow:20 SCCM; gas pressure: 2 Pa; and power: 50 W; the resist material of thethird embodiment had an etching rate of approximately 20% less than thatof the PMMA; thus, the resistance was improved by this rate. On theother hand, regarding the ECR dry etching using Cl₂ gas for etching a Sisubstrate, under etching conditions of gas flow: 40 SCCM; gas pressure:0.05 Pa; and microwave power: 200 W; the resist of the third embodimenthad etching resistance approximately 2 times as high as that of thePMMA; thus, it was proved that by using a resist material with athickness approximately one half of the conventional PMMA, substrateetching with an etching depth approximately as deep as that of theconventional PMMA could be performed also in this case.

Fourth Embodiment

Instead of the hydrogenated fullerene used in the third embodiment, amethyl fullerene comprising a methyl group (manufactured by Tokyo KaseiCo.) was used in the fourth embodiment, and results as good as thoseobtained in the third embodiment could be obtained.

Fifth Embodiment

Instead of the fullerene C₆₀ used in the second embodiment, fullereneC₆₀ including La (manufactured by MER Co.) was used in the fifthembodiment, and almost the same results as the second embodiment couldbe obtained.

Sixth Embodiment

The resist used in this embodiment is SAL601 (manufactured by ShipleyCo.), a conventional chemical amplification negative e-beam resist (thatis, in this negative type, areas which are subjected to high energy beamexposure remain after development, and thereby, a pattern isfabricated). For 100 solid parts by weight of this SAL601, 3 parts byweight of fullerene C₆₀ (manufactured by Tokyo Kasei Co.) wereincorporated so as to form a resist material. After dissolving thefullerene C₆₀ in monochlorobenzene to have 1 wt % concentration, thissolution was mixed into the above SAL601 to make a SAL601 resistsolution including fullerene C₆₀.

Then, a Si substrate was spin-coated with this resist solution at athickness of 100 nm, and after baking at 105° C. for 2 minutes, exposurewas performed using the electron beam exposure machine (50 kV). Afterthe exposure, the substrate was kept in an air environment, so as toperform an experiment for evaluating resist sensitivity. The sensitivityevaluation was performed such that the substrate kept in the airenvironment for a fixed time was baked at 105° C. for 2 minutes, and wasdeveloped using a tetramethylammonium hydroxide aqueous solution of 0.27N (normality) for 6 minutes, and the remaining thickness with respect tothe exposure dose was measured using a film-thickness measurementinstrument.

FIG. 8 shows results of the sensitivity evaluation for the resistmaterial of the present embodiment in comparison with the conventionalchemical amplification SAL601 resist which does not contain thefullerene. That is, this figure is a graph diagram for comparingsensitivity stabilities of a conventional resist material and a resistmaterial according to the present invention. In FIG. 8, the verticalaxis indicates resist sensitivity (%) with a standard level immediatelyafter the exposure, while the horizontal axis indicates thepost-exposure delay time (hour). In addition, black circles and whitecircles in FIG. 8 respectively show results of the resist material ofthe sixth embodiment and the conventional chemical amplification resist.As shown in the figure, the resist material of the present invention hadonly a few percent of sensitivity degradation (with respect to thestandard level immediately after the exposure) even with thepost-exposure delay time of around 100 hours, while in the case of theconventional chemical amplification resist, resist sensitivity wasdecreased by 80% or more. As clearly understood by these results,sensitivity stabilization for the chemical amplification resist can berealized by using a resist material according to the present embodiment.

Seventh Embodiment

The resist used in this embodiment is ZEP520 (manufactured by NipponZeon Co.), a positive e-beam resist, and for 100 solid parts by weightof this ZEP520, 10 parts by weight of fullerene C₆₀ (manufactured byKanto Chemical Co.) were incorporated so as to form a resist material.After dissolving the fullerene C₆₀ in ortho-dichlorobenzene to have 1 wt% concentration, this solution was mixed into the above ZEP520 to make aZEP520 resist solution including fullerene C₆₀.

Then, a Si substrate was spin-coated with this resist solution at athickness of 50 nm, and after baking at 165° C. for 30 minutes, exposurewas performed using the electron beam exposure machine (25 kV). Afterthe exposure, the substrate was developed using n-amyl acetate, astandard developer for the ZEP520 resist, for 3 minutes. In this way, ahigh-contrast pattern approximately the same as the first embodimentcould be fabricated.

In addition, another Si substrate was spin-coated with the resistsolution of the present embodiment at a thickness of 50 nm, and afterbaking at 165° C. for 30 minutes, exposure was performed using theelectron beam exposure machine (25 kV). After the exposure, thesubstrate was developed using diethyl ketone, a strong developer for theZEP520 resist, for 3 minutes, and then the remaining film thickness withrespect to the exposure dose was measured using the film-thicknessmeasurement instrument so as to examine resist sensitivity.

FIG. 9 shows a sensitivity curve of the resist material of the presentembodiment in comparison with that of the conventional ZEP520 resistwhich does not contain the fullerene. That is, FIG. 9 is a graph diagramfor comparing sensitivity (plotted) curves of a conventional resistmaterial and a resist material according to the present invention. InFIG. 9, the vertical axis indicates (the rate of) remaining filmthickness (%: a percentage of a thickness after the development withrespect to the initial thickness before exposure), while the horizontalaxis indicates the exposure dose (μC/cm²). In addition, black circlesand white circles in FIG. 9 respectively show results of the resistmaterial of the seventh embodiment and the conventional resist. As shownby the figure, in both resists, the exposure dose (indicating the resistsensitivity) by which the remaining film thickness becomes 0% was ataround 5 μC/cm²; thus, sensitivity was improved (in the case of usingthe above-mentioned standard developer, the exposure dose correspondingto the “0%” remaining film thickness was 50 μC/cm²). However, in theconventional (pure) ZEP520 resist, it is obvious with reference to FIG.9 that the initial thickness in an unexposed or underexposed area wasdecreased by around 30% due to the usage of a strong developer. That is,in this case, “thickness degradation” occurred and thus the patterncontrast was degraded. In contrast, in the resist material of theseventh embodiment, such thickness degradation was not at all found;therefore, sensitivity could be improved without degradation of thepattern contrast.

In addition, regarding reactive dry etching using O₂ gas or ECR dryetching using Cl₂ gas, etching resistance was improved similar to thesecond embodiment, that is, improvement of etching resistance was alsoconfirmed for the resist material in the seventh embodiment.

Heat resistance of the resist of this seventh embodiment was alsoevaluated. The evaluation was performed such that a Si substrate wasspin-coated with the resist solution of the present embodiment at athickness of 150 nm, and after baking at 165° C. for 30 minutes,exposure was performed using the electron beam exposure machine (25 kV).After the exposure, the substrate was developed using theabove-mentioned standard developer so as to fabricate a pattern with 150nm pitch. The substrate on which the pattern was fabricated was thenbaked in an oven at 100-200° C. for 30 minutes, and a cross section ofthe pattern was observed using a SEM.

FIGS. 10 and 11 are SEM photographs of pattern cross sections (afterbaking) of the resist material according to the seventh embodiment andthe conventional resist, respectively. That is, FIG. 10 is a SEMphotograph showing heat resistance of a fine pattern obtained using aresist material according to the present invention, and FIG. 11 is a SEMphotograph showing heat resistance of a fine pattern obtained using aconventional resist material. As clearly shown by FIGS. 10 and 11, heatresistance was enhanced in the case of the resist material according tothe seventh embodiment.

Furthermore, mechanical resistance of the resist material of thisseventh embodiment was evaluated. The evaluation was performed such thata Si substrate was spin-coated with the resist solution of the presentembodiment at a thickness of 150 nm, and after baking at 165° C. for 30minutes, exposure was performed using the electron beam exposure machine(25 kV). After the exposure, the substrate was developed using n-amylacetate, a standard developer for the ZEP520 resist, for 3 minutes, anda minimum pitch producing acceptable resolution without detachment,collapse, snaking, or sticking of patterns was evaluated. FIGS. 12 and13 are SEM photographs of pattern cross sections showing mechanicalstrengths of the resist material according to the seventh embodiment andthe conventional resist, respectively. That is, FIG. 12 is a SEMphotograph showing mechanical strength of a fine pattern obtained usinga resist material according to the present invention, and FIG. 13 is aSEM photograph showing mechanical strength of a fine pattern obtainedusing a conventional resist material. As clearly shown by FIGS. 12 and13, in the case of the resist material according to the seventhembodiment, good resolution was obtained with respect to a 60 nm pitchpattern, while in the conventional resist, detachment and snaking werefound even with a 90 nm-pitch pattern and thus neighboring parts in thepattern merged with each other. Therefore, the pattern of theconventional resist could not be resolved. This pattern collapse iscaused at the drying of rinse solvent during development process, thatis, the high aspect ratio resist pattern could not stand against surfacetension of the rinse solvent. The incorporation of fullerene acts as thereinforcement of the resist resin, and the mechanical strength can alsobe improved by using a resist material according to the seventhembodiment (for example, in contrast with a pattern aspect ratio of 3 inconventional cases, a pattern aspect ratio of 4-5 can be obtained in thepresent invention under the same conditions).

Eighth Embodiment

The resist used in this embodiment is ZEP520 (manufactured by NipponZeon Co.), a positive e-beam resist, and for 100 solid parts by weightof this ZEP520, 10 parts by weight of a 4/1 mixture of fullereneC₆₀/fullerene C₇₀ (i.e., C_(60/70) :manufactured by Kanto Chemical Co.)were incorporated so as to form a resist material. After dissolving thefullerene C_(60/70) in ortho-dichlorobenzene to have 1 wt %concentration, this solution was mixed into the above ZEP520 to make aZEP520 resist solution including fullerene C_(60/70). Then, a Sisubstrate was spin-coated with this resist solution, and an evaluationexperiment similar to the seventh embodiment was performed. As a result,in the resist material according to the eighth embodiment, improvementsof etching resistance, pattern contrast, sensitivity, heat resistance,and mechanical strength were also realized, as in the case of theseventh embodiment. In addition, instead of C_(60/70), another mixturein which a trace quantity of higher order fullerene is included may beused, and it is more desirable in cost-performance.

Ninth Embodiment

The resist used in this embodiment is ZEP520 (manufactured by NipponZeon Co.), a positive e-beam resist, and for 100 solid parts by weightof this ZEP520, 10 parts by weight of hydrogenated fullerene C₆₀H₃₆(manufactured by MER Co.), a fullerene derivative, were incorporated soas to form a resist material. Then, a Si substrate was spin-coated withthis resist solution, and an evaluation experiment similar to theseventh embodiment was performed. As a result, in the resist materialaccording to the ninth embodiment, improvements of etching resistance,pattern contrast, sensitivity, heat resistance, and mechanical strengthwere also realized, as in the case of the seventh embodiment.

Tenth Embodiment

The resist used in this embodiment is ZEP520 (manufactured by NipponZeon Co.), a positive e-beam resist, and for 100 solid parts by weightof this ZEP520, 10 parts by weight of hydrogenated fullerene C₆₀H₁₈(manufactured by MER Co.), a fullerene derivative, were incorporated soas to form a resist material. Then, a Si substrate was spin-coated withthis resist solution, and an evaluation experiment similar to theseventh embodiment was performed. As a result, in the resist materialaccording to the tenth embodiment, improvements of etching resistance,pattern contrast, sensitivity, heat resistance, and mechanical strengthwere also realized, as in the case of the seventh embodiment.

Eleventh Embodiment

The resist used in this embodiment is ZEP520 (manufactured by NipponZeon Co.), a positive e-beam resist, and for 100 solid parts by weightof this ZEP520, 10 parts by weight of an approximately 1/1 mixture offullerene C₆₀ (manufactured by Kanto Chemical Co.)/hydrogenatedfullerene C₆₀H₃₆ (manufactured by MER Co.) were incorporated so as toform a resist material. Then, a Si substrate was spin-coated with thisresist solution, and an evaluation experiment similar to the seventhembodiment was performed. As a result, in the resist material accordingto the eleventh embodiment, improvements of etching resistance, patterncontrast, sensitivity, heat resistance, and mechanical strength werealso realized, as in the case of the seventh embodiment.

Twelfth Embodiment

The resist used in this embodiment is ZEP520 (manufactured by NipponZeon Co.), a positive e-beam resist, and for 100 solid parts by weightof this ZEP520, 10 parts by weight of an approximately 1/1 mixture offullerene C₆₀ (manufactured by Kanto Chemical Co.)/hydrogenatedfullerene C₆₀H₁₈ (manufactured by MER Co.) were incorporated so as toform a resist material. Then, a Si substrate was spin-coated with thisresist solution, and an evaluation experiment similar to the seventhembodiment was performed. As a result, in the resist material accordingto the twelfth embodiment, improvements of etching resistance, patterncontrast, sensitivity, heat resistance, and mechanical strength werealso realized, as in the case of the seventh embodiment.

Thirteenth Embodiment

The resist used in this embodiment is ZEP520 (manufactured by NipponZeon Co.), a positive e-beam resist, and for 100 solid parts by weightof this ZEP520, 10 parts by weight of an approximately 1/1/1 mixture offullerene C₆₀ (manufactured by Kanto Chemical Co.)/fullerene C₇₀(manufactured by Kanto Chemical Co.)/hydrogenated fullerene C₆₀H₃₆(manufactured by MER Co.) were incorporated so as to form a resistmaterial. By mixing various materials in this way, solubility can bemuch improved. Then, a Si substrate was spin-coated with this resistsolution, and an evaluation experiment similar to the seventh embodimentwas performed. As a result, in the resist material according to thethirteenth embodiment, improvements of etching resistance, patterncontrast, sensitivity, heat resistance, and mechanical strength werealso realized, as in the case of the seventh embodiment.

Fourteenth Embodiment

The resist used in this embodiment is ZEP520 (manufactured by NipponZeon Co.), a positive e-beam resist, and for 100 solid parts by weightof this ZEP520, 10 parts by weight of an approximately 1/1/1/1 mixtureof fullerene C₆₀ (manufactured by Kanto Chemical Co.)/fullerene C₇₀(manufactured by Kanto Chemical Co.)/hydrogenated fullerene C₆₀H₁₈(manufactured by MER Co.)/hydrogenated fullerene C₆₀H₃₆ (manufactured byMER Co.) were incorporated so as to form a resist material. Then, a Sisubstrate was spin-coated with this resist solution, and an evaluationexperiment similar to the seventh embodiment was performed. As a result,in the resist material according to the fourteenth embodiment,improvements of etching resistance, pattern contrast, sensitivity, heatresistance, and mechanical strength were also realized, as in the caseof the seventh embodiment.

Fifteenth Embodiment

The resist used in this embodiment is EBR-9 (manufactured by Toray Co.),a fluorine-included acrylic main chain scission type positive e-beamresist, and for 100 solid parts by weight of this resist, 10 parts byweight of a 4/1 mixture of fullerene C₆₀/fullerene C₇₀ (i.e., C_(60/70)manufactured by Kanto Chemical Co.) were incorporated so as to form aresist material. After dissolving the fullerene C_(60/70) inortho-dichlorobenzene to have 1 wt % concentration, this solution wasmixed into the above EBR-9 to make an EBR-9 resist solution includingfullerene C_(60/70). Then, a Si substrate was spin-coated with thisresist solution, and an evaluation experiment similar to the seventhembodiment was performed. As a result, in the resist material accordingto the fifteenth embodiment, improvements of etching resistance, patterncontrast, sensitivity, heat resistance, and mechanical strength werealso realized, as in the case of the seventh embodiment.

Sixteenth Embodiment

The resist used in this embodiment is ZEP-AC134 (manufactured by NipponZeon Co.), a chemical amplification positive e-beam resist, and for 100solid parts by weight of this resist, 10 parts by weight of fullereneC₆₀ (manufactured by Kanto Chemical Co.) were incorporated so as to forma resist material. After dissolving the fullerene C₆₀ inortho-dichlorobenzene to have 1 wt % concentration, this solution wasmixed into the above ZEP-AC134 to make a ZEP-AC134 resist solutionincluding fullerene C₆₀. Then, a Si substrate was spin-coated with thisresist solution, and an evaluation experiment similar to the seventhembodiment was performed. As a result, in the resist material accordingto the sixteenth embodiment, improvements of etching resistance, patterncontrast, sensitivity, heat resistance, and mechanical strength werealso realized, as in the case of the seventh embodiment. In the abovesixth embodiment, sensitivity stabilization was shown with an example ofa standard chemical amplification “negative” e-beam resist. In thepresent case of the chemical amplification “positive” e-beam resistaccording to the present invention, sensitivity stabilization could alsobe realized.

Seventeenth Embodiment

The resist used in this embodiment is chloromethylated polystyrene(CMS), a crosslinking type negative e-beam resist comprising achloromethyl group, and for 100 solid parts by weight of this resist, 5parts by weight of fullerene C₆₀ (manufactured by Kanto Chemical Co.)were incorporated so as to form a resist material. After dissolving thefullerene C₆₀ in ortho-dichlorobenzene to have 1 wt % concentration,this solution was mixed into the above CMS to make a CMS resist solutionincluding fullerene C₆₀. Then, a Si substrate was spin-coated with thisresist solution, and an evaluation experiment similar to the seventhembodiment was performed. As a result, in the resist material accordingto the seventeenth embodiment, improvements of etching resistance, heatresistance, and mechanical strength were also realized, as in the caseof the seventh embodiment.

Eighteenth Embodiment

The resist used in this embodiment is RI-1210N (manufactured by HitachiChemical Co., Ltd.), a negative e-beam resist, and for 100 solid partsby weight of this resist, 5 parts by weight of fullerene C₆₀(manufactured by Kanto Chemical Co.) were incorporated so as to form aresist material. After dissolving the fullerene C₆₀ inortho-dichlorobenzene to have 1 wt % concentration, this solution wasmixed into the above RI-1210N to make an RI-1210N resist solutionincluding fullerene C₆₀. Then, a Si substrate was spin-coated with thisresist solution, and an evaluation experiment similar to the seventhembodiment was performed. As a result, in the resist material accordingto the eighteenth embodiment, improvements of etching resistance,pattern contrast, sensitivity, heat resistance, and mechanical strengthwere also realized, as in the case of the seventh embodiment.

Nineteenth Embodiment

The resist used in this embodiment is a photoresist THMR-iP3300(manufactured by Tokyo Ohka Kogyo Co.), and for 100 solid parts byweight of this resist, 7 parts by weight of fullerene C₆₀ (manufacturedby Tokyo Kasei Co.) were incorporated so as to form a resist material.After dissolving the fullerene C₆₀ in ortho-dichlorobenzene to have 1 wt% concentration, this solution was mixed into the above THMR-iP3300 tomake a THMR-iP₃₃₀₀ resist solution including fullerene C₆₀. Then, a Sisubstrate was spin-coated with this resist solution, and an evaluationexperiment similar to the seventh embodiment was performed using areduction projection exposure tool. As a result, in the resist materialaccording to the nineteenth embodiment, improvements of etchingresistance, pattern contrast, sensitivity, heat resistance, andmechanical strength were also realized, as in the case of the seventhembodiment. In this nineteenth embodiment, the THMR-iP3300 resist whichhas generally been used in the exposure process for circuit patterns ofthe ULSI was used; however, the present invention may also be applied toall types of photoresists including a resist for the excimer laser.Furthermore, in addition to C₆₀, another fullerene or fullerenederivative, such as C₇₀ or C₆₀H₃₆ may also be used, as described above.

What is claimed is:
 1. A method for fabricating a resist material, byrepeatedly performing: a first step of coating a substrate with a resistfilm; and a second step of depositing particles whose major component isa cluster of carbon atoms on the resist film.
 2. A resist materialhaving a resist and particles whose major component is a cluster ofcarbon atoms, wherein a resist film and the particles are alternativelydeposited on a substrate.